A hack to add an internal BlueTooth connection to your iMX515 tablet.This is not as complex as the RS232 hack since we do not need to modify any Boot-loader or kernel software, however the connection points need to match or there is a potential risk of corrupting your SD-card.Basically that means as long as you follow the details in this documented hack , you should be OK. But if you start to get 'clever' and attempt to connect the hack to a different point, there is the potential to corrupt the SD-card, during system boot.(See below)

Warnings

USBThere are two USB connection on the iMX515 APAD CPU board.Please be 100% clear that one port is buffered by a external secondary USB controller.The Other port is NOT buffered and leads directly into the CPU

Power SupplyFor this hack we have utilized the 3V3 power supply, normally a USB peripheral would run from the 5 volt line,we have utilized the 3V3 line for a number of reasons:

Too allow further power control, since the 3V3 line we have utilized is switched via the power control chip

Too limit down the TX power of the Blue Tooth adaptor

We do not need to worry about shorting the 5v0 line into the CPU board or into the input circuitry associated with the CPU

You're the one that I wantAs highlighted previously there are two USB ports available, for this hack we have utilized the buffered USB connection that is provided via the USB3317.Utilizing the USB connection into the CPU is possible, but it causes the kernel to issue backtrace errors during the initialization of the USB chain.

to corruption of the SD-card, as a result it is generally a good idea to stick with the hack as shown, unless you have the capability to re-write the SD-card image, be aware that a full image is required, rather than just a partition update, since the above appears to cause low level filesystem corruption rather than just corruption of the enclosed files.

Usual disclaimers apply:

If you screw up your SD-card it is on YOU.

if your dog dies an unexplained death it is on you.

if you completely destroy your tablet it is on you.

That said, if you follow the instructions reasonably closely, then you should have success.

Only TWO rules:

Disconnect the battery negative connection during the hack.YOU MUST DO THIS, because even if your tablet appears to be 'off' it is not really 'off' since the battery is still supplying standby power to various peripheral circuitry.Soldering onto powered CMOS circuitry really is not recommended.

Ensure you follow Anti-static procedures, since you could be injecting charge into the CPU USB ports

First thing you will need is a standard BlueTooth dongle(one that does not need drivers)

CAREFULLY Strip the BlueTooth dongle out of its plastic housing, so that you have just the PCB.try not to finger it too much, unless you are wearing an Anti-static wrist strap.

Locate four lengths of Teflon or PVC coated cable (10 CM should be enough)Strip and tin both ends of the cable, it would also be a good idea to make the D+ and D- a twisted pair rather than just a pair of straight wires.Do not twist the 0V and the Pwr into this set, since D+ and D- form a balanced differential pair, also try to keep these two wires exactly the same physical length so as to reduce any large data signal shifts.

Start by soldering the BlueTooth dongle end first:

Connecting to the main APad PCBMake the connection to the D+ & D-, followed by the Pwr and finally the 0V connection.

Recognition by the APad Android systemIn the following image we can clearly see that the Bluetooth hack seems to be performing admirably, recognizing both my Main OS X system and my Sony Ericsson mobile Phone. (No my name is not bob.... bob is my invisible helper: that in itself it is a very funny story)

This modification obviously opens up the potential for some interesting software hacks and also the option to port over to a Pad computer, one or more of the many Linux penetration testing frameworks and it opens up options to add additional items inside the tablet system including RFID readers, basically things you may need to carry about without being too obvious.

EpilogueThe hack has been tested for about two weeks as regards to stability and not damaging the PCB or battery, and seems to be functioning correctly.You will notice that I have not yet converted the D+ & D- cables into a twisted pair, this is so that I can that the stability of the connection and to see if not making a twisted pair actually effects the functionality of the BlueTooth or the other WI-FI connection.

Once I have made a decision I will then Modify the power connection to the 5V0 power supply to see if the hack is still stable and finally I will tidy up the wires and BlueTooth PCB location so that the APad case can be reassembled.

Also shown is its position in relation to the other wires. Note that the sound hack has also been relocated off that power connection, this was to aid possible future disassembly of the PCB's.

The 'dandruff' all over the PCB is actually dust, In china you cannot leave anything out in the open for more than a few days before it is covered in dust even in the countryside. You can imagine that this play havoc with any sort of uncovered electrical appliances and food.

After double checking all connections and re-soldered the data ones and the bluetooth came to life for a moment After the reset when Turning on, apparently tries to activate it but after 5 secs goes to off.

Did you need to install any drivers or do something? The BT used was the one in the following picture:

Absolutely NO software mods were made...But you may need to enable bluetooth in Android from within the configuration utility.If the bluetooth device is connected correctly, then it should work, or at the very least show up in the Linux kernel log.

Unfortunately even using your picture cannot identify the chip inside the Bluetooth dongle, because that is a standard case, the PCB & internal chip varies depending on where & from whome you bought the blue-tooth dongle

Yep, Try taking a look in the Kernel startup logs, basically when linux boots up, it writes the information into a log file as well as to the RS232 port.In that boot file you will find all the devices identified by linux, if you cannot see the Blue tooth device , then it means a driver is required (normally this is very rare, since the USB bluetooth is supposed to be standard)

But........Having said that I see, if we do a Google search on the chip 'as3620qa' there are a number of people complaining this chip does not work, with..... Windows, Vista and that it needs a driver.See if the device packaging had a small disk with a driver on it, if so ... you need a bluetooth device that does not require a driver.Alternatively you can try and find a driver for 'arm-Linux' or source code. (personally I would go for a driverless bluetooth device)

So the plan of action:1. Find out the requirements of Blue-tooth chip.2 Decide if to proceed (go to 3 )or try another bluetooth adaptor(goto 1) this was my initial plan, I just went out and bought 3 different types.

3. Find the linux Boot log file4. Make an RS232 terminal connection to the board.5. Try to debug the system

P.S...

pls show your connections at the CPU board end, I just need to see if you have the connections in the right order.

Basically, It is down to the Bluetooth chipset and the drivers, and the make of the tablet.Since the Chinese suppliers do not share the code or changes they make to the kernel and as a result getting this stuff to work can be flakey at best.........